This invention relates generally to means for mounting a seat and in particular to a boat seat mounting unit adapted to be clamped onto a boat thwart.
On smaller boats, such as for instance a johnboat or other fishing or game-type boat, thwarts serve not only for structural support between the gunwales but also as seats for the boatman and passengers. Inasmuch as a thwart seat does not provide any back support, however, it is oftentimes desirable to mount a seat such as a plastic or fiber glass molded contour seat (often referred to as a "legless chair") on the thwart. It is also advantageous to be able to quickly and easily mount the seat and to demount it from a thwart seat rather than having it permanently attached thereto so that the seat may be readily be transferred from one boat to another and stored during nonuse. With the seat removed, the boat may more readily be transported in inverted position on top of a car or stacked with other boats in nested fashion. Moreover, it is often convenient to be able to quickly and easily reposition the seat on the thwart in order to fish from a different location in the boat and also to keep the boat in trim and on an even keel under various load conditions.
Boat seat mounting units of the clamp-on type have been known in the past and are shown on page 271 of the 1976 Wholesale Distributors Catalogue published by Covert Marine, and in U.S. Pat. Nos. 3,789,444, issued Feb. 5, 1974, and 3,113,804, issued Dec. 10, 1963. Heretofore, however, mounting units of this type have presented certain problems, one being that they did not grip the thwart with sufficient force to rigidly mount the boat seat on the thwart, thus resulting in the tendency of the boat seat to slide on the thwart upon any sudden movement of the person in the seat. The seat would sometimes even pop off the thwart entirely. In addition, many units were adjustable to fit only thwarts having widths falling within a very narrow range, and adjustments were time-consuming and tedious to make. These prior art units were also limited as to the types of thwarts on which they could be mounted. Many units, for example, could be properly mounted only on a thwart having a top surface overhanging the thwart sides.